add support dual system

by github.com/m1cha

Change-Id: I486c129c2f75e14911f80bac8df7c338030ef8cd
Merge branch 'cm-10.2' of https://github.com/CyanogenMod/android_system_core into cm-10.2

Change-Id: I08cfe6e7d718cd9428ebedb4727e15256cb1433e
Merge pull request #1 from CyanogenMod/cm-10.2

merge the newest cm-10.2 codes
Merge pull request #1 from mitwo-dev/cm-10.2

Cm 10.2